Why do so few companies use the Dojo Toolkit?

Dojo is fantastic software, but it does a lot more than the other libraries and consequently has a much higher learning curve. It’s advanced features may serve as something of a disadvantage for achieving more widespread adoption—most developers don’t need the more advanced abstractions provided by Dojo when they start their projects, and by the time they DO need that stuff they’ve already written a ton of code using another library!